Changes Application - MCU15/0023.02

ProjectNo.112.14608
January,2013 REF: 1-14608,2013.01-15,BR VER O.                                                              Page16

     Until the base of the wall is prevented from inward movement by the strutting action. the
     resistance of movement is provided by the friction of the soil beneath the base slab, and
     by the passive resistance of the soil against the vertical face of the toe of the wall. The
     intensity of passive resistance can be calculated from:-



                P          =          0.5 K, Y Hz'
                Kp         =          passive pressure coefficient
                H,         =          front face of wall contributing to passive resistance (m)

     Pool side walls should be designed using a pressure coefficient for the at rest condition,
     Ko.


     The lateral pressure distributions shown in Figure 3 includes hydrostatic pressure and
     show typical surcharge loadings pressure distribution.                       Due to possible long term
     problems with blocking of gravel filters and drains and short term storm conditions that
     could flood the fill behind retaining walls, it is recommended that all retaining walls be
     designed for some water pressure distribution.                A suggested water pressure distribution
     for retaining walls on this site would be one third height water pressure.


     For the calculation of sliding resistance, base friction for walls without a key may be taken
     as tan (2/3 0). If the wall has a shallow base key the shearing resistance may be based
     on tan 0. Refer to Table 6 for the friction angle of sand.


     TABLE 6               RETAINING WALL DESIGN PARAMETERS

              Material             Density              Earth Pressure Coefficient                   Long Term
                                   (kNlm')           Ka               Ko               Kp            Drained '"
                                                                                                      (degrees)
           Compacted Fill '           19            0.41             0.58             2.46                25
                 Fill'                17            0.27             0.43             3.69                35
             Loose Sand               17            0.33             0.50             3.00                30
       Medium Dense Sand              18             0.29            0.46             3.39                33
          Dense Sand                  19             0.27             0.43             3.69              35
      Notes:-
              1) If fill is compacted against a retaining wall the actual earth pressure could exceed the vertical
                 pressure(ie.Ka > 1.0).
              2) Infers granular free draining material placed behind the retaining wall as a drainage layer.




                                                                    ;If SOIL SURVEYS ENGINEERING